Madsen's Shop
& Supply Inc.

Professional Saw Chain -
Understanding Cutter Teeth

In the Pacific Northwest, there is one type of saw chain that
most professional chain saw users use: square-ground chisel bit. To
fully understand why so many professional saw users prefer this
chain, you must
first understand some basics about chain saw cutter teeth.

Cutter Tooth
Shapes

There are two basic shapes of cutter teeth. One style we call:
round, and the other we call: square. The images below show these basic
shapes. The one on the left is round or "chipper" cutter
tooth. The image in the middle is a square
or "chisel" cutter tooth. Both are sharpened round. The tooth
on the right is also square tooth, but it has been ground
"square." This language may be a little confusing, but a study the
images
below should make these differences understandable. They depict all the
basic shapes and grinds that are made.

Which Cutter Is Best?

The answer to this really depends on you. Factors like
the saw you run, the work you do, how you sharpen you chain,
and
so on, all play a part in determining which cutter is best. The
following highlights characteristics of each
type:

Round Chain
-
This chain is the easiest
to sharpen. An average user can do it with a round file and have good
results. It also has the best stay-sharp-ability of the three cutter
teeth. Its cutting edge is more
durable that those on either square tooth chain. This can be
explained by the fact that the edge on a round cutter tooth
is larger and better supported.

Square
Tooth Round Ground - This chain cuts
10-15% faster than round chain on most saws. Since it takes
less power for a sharp square cutter tooth to
sever wood fiber, square tooth chain almost
always improves a saw's cutting performance. This chain can
also be sharpened with
a round file, so it is fairly easy to maintain for an average user.
While it outperforms round cutters when it is sharp,
its stay-sharp-ability is not as good.

Square Tooth
Square Ground - This chain cuts 20-25% better
than round chain. A square ground chisel cutter tooth is the most
efficient of the three. It offers the best cutting performance of all
the cutter teeth when it is sharp. This chain can be sharpened with a
special file, but most pro users sharpen it with a special square
grinder. It is not a chain that is easy to maintain for an average
user. Its stay-sharp-ability is also the least of the three
styles of cutter teeth.

Our Advice

If you are a professional timber faller working in the
Pacific Northwest or Alaska, use square
ground
chisel chain.

If you use square ground chisel chain, buy a chisel
grinder or become friends with someone who owns one. Filing square
ground chisel chain is very difficult. Few people do it well. Of those
who can file it, most would do an even better job if they had a
grinder.

If you cut cedar, salvage, or work in dirty
conditions,
use round chain. It is easier to sharpen and will hold its edge
better for you.

If you are working in clean wood and want the best cutting
performance, but can't afford a square grinder, use round ground
chisel chain. This chain performs well, is fairly easy to sharpen with
a file, and will out-cut poorly filed square chisel chain every
time.

This is a close-up photo of a square-ground chisel
cutter tooth. The sharp angles and precise alignment in its corner make
this a very efficient cutter tooth, but this corner is fragile. It
performs best in clean softwood trees.

A Few More Thoughts

The stay-sharp
advantage of round chain is mostly seen when working in
dirty or light-abrasive conditions. A chain's
stay-sharp-ability
should not be confused with a chain becoming dull due to "rocking."
Hitting a rock or other
hard material will dull any cutter tooth -- round or square.

You will notice that
harvester chain always has round cutter teeth. This type of tooth works
best in this
application because a round cutter tooth offers the best
stay-sharp-ability. It
is also the easiest chain for most operators to hand sharpen.
Since harvesters are powered by a large diesel engine, a chain's
cutting efficiency is not as big of a factor in cutting performance as
it is with hand-held chain saws.